bool find_first_value_node(const synfig::ValueNode::Handle& value_node, Gtk::TreeIter& iter);
bool find_next_value_node(const synfig::ValueNode::Handle& value_node, Gtk::TreeIter& iter);
bool find_first_value_node(const synfig::ValueNode::Handle& value_node, Gtk::TreeIter& iter);
bool find_next_value_node(const synfig::ValueNode::Handle& value_node, Gtk::TreeIter& iter);
static CellRenderer_ValueBase* add_cell_renderer_value(Gtk::TreeView::Column* column);
static CellRenderer_TimeTrack* add_cell_renderer_value_node(Gtk::TreeView::Column* column);
static CellRenderer_ValueBase* add_cell_renderer_value(Gtk::TreeView::Column* column);
static CellRenderer_TimeTrack* add_cell_renderer_value_node(Gtk::TreeView::Column* column);